Interface TypeHierarchyProvider

interface TypeHierarchyProvider {
    prepareTypeHierarchy(
        document: LangiumDocument,
        params: TypeHierarchyPrepareParams,
        cancelToken?: Cancellation.CancellationToken,
    ): MaybePromise<undefined | TypeHierarchyItem[]>;
    subtypes(
        params: TypeHierarchySubtypesParams,
        cancelToken?: Cancellation.CancellationToken,
    ): MaybePromise<undefined | TypeHierarchyItem[]>;
    supertypes(
        params: TypeHierarchySupertypesParams,
        cancelToken?: Cancellation.CancellationToken,
    ): MaybePromise<undefined | TypeHierarchyItem[]>;
}